Android的handler異步更新實例

 方法一:

package com.example.handlerdemo; 
 
import org.apache.http.HttpResponse; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 
 
import android.app.Activity; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.view.View; 
import android.widget.ImageView; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
    private static final int MSG_SUCCESS = 0;// 獲取圖片成功的標識 
    private static final int MSG_FAILURE = 1;// 獲取圖片失敗的標識 
    ImageView mImageView; 
    Handler mHandler = new Handler() { 
        public void handleMessage(Message msg) { 
            switch (msg.what) { 
            case MSG_SUCCESS: 
                mImageView.setImageBitmap((Bitmap) msg.obj);// imageview顯示從網絡獲取到的logo 
                break; 
            case MSG_FAILURE: 
                Toast.makeText(getApplication(), "下載失敗", Toast.LENGTH_LONG) 
                        .show(); 
                break; 
            } 
        } 
    };protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
        mImageView = (ImageView) findViewById(R.id.imageView1);// 顯示圖片的ImageView 
 
    } 
 
    public void onClick(View v) { 
        switch (v.getId()) { 
        case R.id.button1: 
            mImageView.setImageBitmap(null); 
            new Thread(new Runnable() { 
                public void run() { 
                    HttpClient hc = new DefaultHttpClient(); 
                    HttpGet hg = new HttpGet( 
                            "http://www.baidu.com/img/baidu_sylogo1.gif");// 獲取百度的LOGO 
                    final Bitmap bm; 
                    try { 
                        HttpResponse hr = hc.execute(hg); 
                        bm = BitmapFactory.decodeStream(hr.getEntity() 
                                .getContent()); 
                    } catch (Exception e) { 
                        mHandler.obtainMessage(MSG_FAILURE).sendToTarget();// 獲取圖片失敗 
                        return; 
                    } 
                    mHandler.obtainMessage(MSG_SUCCESS, bm).sendToTarget();// 獲取圖片成功，向ui線程發送MSG_SUCCESS標識和bitmap對象 
 
                } 
            }).start(); 
            break; 
        } 
    } 
} 

不過這個方法有個小問題 老是提示會內存洩露

方法二:

package com.example.handlerdemo; 
 
import org.apache.http.HttpResponse; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 
 
import android.app.Activity; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.view.View; 
import android.widget.ImageView; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
 
    ImageView mImageView; 
 
    Handler mHandler02 = new Handler(); 
 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
        mImageView = (ImageView) findViewById(R.id.imageView1);// 顯示圖片的ImageView 
 
    } 
 
    public void onClick(View v) { 
        switch (v.getId()) { 
        case R.id.button2: 
            mImageView.setImageBitmap(null); 
            new Thread(new Runnable() { 
                public void run() { 
                    HttpClient hc = new DefaultHttpClient(); 
                    HttpGet hg = new HttpGet( 
                            "http://www.baidu.com/img/baidu_sylogo1.gif");// 獲取百度的LOGO 
                    try { 
                        HttpResponse hr = hc.execute(hg); 
                        final Bitmap bm = BitmapFactory.decodeStream(hr.getEntity() 
                                .getContent()); 
                        mHandler02.post(new Runnable() { 
                            public void run() { 
                                mImageView.setImageBitmap(bm);// imageview顯示從網絡獲取到的logo 
                            } 
                        }); 
                    } catch (Exception e) { 
                        mHandler02.post(new Runnable() { 
                            public void run() { 
                                Toast.makeText(getApplication(), "下載失敗", 
                                        Toast.LENGTH_LONG).show(); 
                            } 
                        }); 
                    } 
                     
                } 
            }).start(); 
            break; 
        default: 
            break; 
        } 
    } 
} 

用方法二是不會出內存洩露的警告的

效果圖:

csdn下載地址:http://download.csdn.net/detail/wenwei19861106/4868799